I would expect him to more than "feel out" your ex. He made a mistake in taking your ex. as a client. He needs to give your ex. some referral names and explain to him why they change has to be made. Accept no less. (Do give him a bit of time to put that process into place, but it shouldn't take much time.) AND, I would absolutely instinst that in the meantime your sessions should NEVER fall on the same day. There is no reason you should in any way have to be exposed to your ex. without your own choosing.